JPS623606B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a high-frequency power amplifier inserted in the middle of a transmission line using a waveguide, and in particular to a built-in waveguide type that is miniaturized, stabilized, and has low loss. This is an attempt to achieve the following.

Prior Art and Problems A power amplifier used in the middle of a transmission line using a waveguide has a problem with coupling with the waveguide at the insertion point. That is, conventionally, as shown in FIG. 1, an amplifier 1 of a microwave integrated circuit (MIC) has a mode conversion waveguide 2, 3 interposed on its input and output sides, and a waveguide 4 for a transmission line. , 5, but this method requires an increase in space and mode conversion loss due to the insertion of the waveguides 2 and 3. Furthermore, the connection between the waveguides 2 and 3 and the amplifier 1 is connected to the input and output terminals of the amplifier. Since the conductor piece 1c is simply brought into contact with the ridges 2a and 3a of the waveguides 2 and 3, the reliability of the connection (pressure contact) becomes a problem. Note that 1b is an amplification element such as an FET.

OBJECTS OF THE INVENTION The present invention attempts to solve the above-mentioned problems by incorporating an amplifier inside a waveguide, and coupling between the input and output terminals of the amplifier and the electromagnetic field inside the waveguide is performed by an antenna.

Structure of the Invention The present invention comprises a metal block disposed inside a waveguide constituting a signal transmission path and fixed within the amplifier waveguide, a dielectric substrate fixed on the metal block, and a dielectric substrate fixed on the metal block. A pair of strip-shaped conductors formed on the front surface of the substrate, receiving and transmitting antennas at the tips thereof, an amplifying element to which the pair of conductors are connected to input and output terminals, respectively, and an amplifier provided on the back surface of the substrate. and a back surface pattern which forms a microstrip line for matching the amplification element together with the conductor and has a tapered tip and matches the impedance of the antenna. This will be explained in detail with reference to the drawings.

Embodiment of the invention FIG. 2 is a schematic diagram showing an embodiment of the invention.
0 is a short waveguide inserted between waveguides 4 and 5 constituting the signal transmission path, 11 is the bottom surface 1 of the waveguide 10
0a is a fixed metal block, 12 is a high frequency power amplifier with a MIC structure fixed on the top thereof, 1
3 and 14 are bias terminals for the amplification element. FIG. 3 is a detailed diagram of the amplifier 12, in which 20 is an amplifying element (for example, a package type FET), 21, 22
is a dielectric substrate divided into two parts (the element 20 may be mounted in the center of one board), 23 and 24 are surface patterns (conductors), and 25 is a back surface pattern (conductor 24).
It is also on the side).

The base of the surface patterns 23 and 24, that is, the amplification element 2
The zero side constitutes a microstrip line as shown in FIG. 5 together with the back pattern 25, and the tips serve as transmitting and receiving antennas, respectively. The gate electrode G and drain electrode D of the FET 20 are connected to the bases of the surface patterns 23 and 24 by soldering, wire bonding, or the like. This surface pattern 2
Matching adjustment elements 27 and 28 are provided at the bases of the FETs 3 and 24, and are used for accurate impedance matching with the FET 20. In other words, even if the amplifying element is of the same standard, the S parameter will vary, and the frequency vs. gain G characteristic will be the expected characteristic C ₁ as shown in C ₂ in Figure 6.
It may deviate from the To correct this, the third
It is preferable to wire-bond a plurality of conductor thin films indicated by small squares in the figure to the front surface patterns 23 and 24 as appropriate to adjust the capacitance with the rear surface patterns. Fourth
The figure is an equivalent circuit diagram, where -Vg is a negative bias voltage for the gate electrode G, and +Vd is a positive bias voltage for the drain electrode D (the source electrode S is grounded through the metal block 11). In addition, the surface patterns 29 and 30 are the surface patterns 23 (24 is the same)
This is due to the branch pattern 31.

The tip of the tapered back pattern 25 is used for impedance adjustment so that the front pattern 23 can efficiently function as an antenna. normal
In the MIC structure, the back surface has a uniform ground pattern, but in this example, this is a tapered pattern 25, and the capacitance with respect to the surface pattern 23 is adjusted (gradually increasing when viewed from the tip side) to achieve an optimal matching state with less reflection. I'm trying to get it.

Effects of the Invention The high frequency power amplifier of the present invention described above has the following advantages. (1) Since two rigid waveguides for mode conversion are not required, less space is required. (2)
Since a microstrip matching circuit with a tapered back surface pattern and front surface pattern is used, input and output to and from the amplifying element can be performed efficiently. (3) Since the amplifier and the transmission line are connected by antenna coupling, there are no problems such as poor contact, and the reliability of the connection is high. (4) When connecting amplifiers in multiple stages, waveguide with built-in amplifier 1
It is sufficient to connect a plurality of 0's in cascade, and since the coupling is antenna coupling and has a DC cut function, there is no need to use a separate DC (bias) cut capacitor as in the case of multi-stage transistor connections.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a conventional high-frequency power amplifier, FIG. 2 is a schematic diagram showing an embodiment of the present invention, and FIGS. 3 a and 3 are a plan view and side view of the main parts.
FIG. 4 is an equivalent circuit diagram, FIG. 5 is a schematic perspective view of a microstrip line, and FIG. 6 is a frequency gain characteristic diagram. In the figure, 4 and 5 are waveguides for transmission paths, 10 is an amplifier waveguide, 11 is a metal block, 12 is a high frequency power amplifier, 13 and 14 are bias terminals, 20 is an amplification element, and 21 and 22 are Dielectric substrate, 23, 24
is the front pattern, 25 is the back pattern, 27,2
8 is a matching adjustment circuit.

Claims (1)

[Claims] 1. A metal block placed inside a waveguide constituting a signal transmission path and fixed within the amplifier waveguide, a dielectric substrate fixed on the metal block, and a dielectric substrate formed on the surface of the substrate. a pair of strip-shaped conductors and receiving and transmitting antennas at their tips; an amplifying element to which the pair of conductors are connected to input and output terminals, respectively; 1. A high frequency power amplifier comprising a microstrip line for matching an amplifying element, and a back pattern having a tapered tip and matching the impedance of the antenna.